A game of catch and listening
The Beavers stand in a circle with the leader in the middle. The ball is thrown to each in turn and the leader calls catch it or drop it. The beavers must do the opposite. If they get it wrong they must drop down on one knee, returning to standing if they get it right next time round or onto two knees if they get it wrong twice on a row. The winner is the last left standing. As a variation, for older children use head it / catch it.